CMV-specific CD19 CAR T cells amplified in vivo using CMV Triplex vaccine for B-NHL

PROJECT SUMMARY Non-Hodgkin’s Lymphoma (NHL) is the most common hematological malignancy worldwide and represents the 6th leading cause of cancer deaths in the United States. Most patients with aggressive B-cell NHL (B-NHL) are initially treated with combination chemoimmunotherapy, with ~2/3 cured. Standard 2nd-line treatment for patients with primary refractory or early relapsed B-NHL is autologous CD19 CAR T cells, while for patients with later relapse it is chemoimmunotherapy followed by autologous hematopoietic cell transplantation (auto HCT). Although CAR T cells and auto HCT can potentially lead to cure, most patients will not achieve lasting remission with either approach. CAR T-cell therapy is hampered by the limited persistence of CAR T cells in patients, and their tendency, even when persisting, to become exhausted and lose their lymphoma-killing ability. We propose a novel approach to improve the efficacy and durability of CAR T cells based on the properties of cytomegalovirus (CMV)-specific T cells that we select and then expand using the Triplex three-antigen CMV vaccine developed at City of Hope. Triplex has proven safe and powerfully immunogenic in both CMV-exposed and non-exposed healthy volunteers and recipients of auto and allogeneic HCT in Phase 1 and 2 clinical trials at multiple US cancer centers. Our approach entails selecting CMVpp65-specific T cells for modification with a CD19-targeting CAR, infusing bi-specific CMV-CD19 CAR T cells into patients, and then inducing expansion in the patient by stimulating the native CMVpp65-specific T cell receptor (TCR) using Triplex viral vaccine. The proposed strategy is designed to enhance proliferation, lengthen persistence, prevent T cell exhaustion, and augment anti- lymphoma activity of CMV-CD19CAR T cells by re-stimulating these cells through the native CMVpp65-specific TCR. The long-term goal of this strategy is improved progression-free survival for B-NHL patients. In Specific Aim 1 (SA1), we will test CMV-CD19 CAR T cell therapy followed by Triplex vaccine in 2 recently initiated pilot clinical trials: 1) for patients with active relapsed/refractory B-NHL following lymphodepleting chemotherapy (NCT05801913), and 2) for patients in 2nd remission to augment auto HCT (NCT05432635). The primary objective is to establish safety and feasibility of the regimen. Secondary objectives are to evaluate clinical and immunological response to therapy. In SA2, we will investigate cellular and molecular characteristics of the CMV- CD19CAR T cell product including immunologic phenotype, functionality, and frequency of bi-specific vs mono- specific target subsets. Following CMV-CD19CAR T cell infusion we will assess expansion kinetics and phenotype of infused cells and their target subsets, pre- and post-Triplex vaccination. These studies will help us to understand differences between TCR and CAR signaling and their impact on CAR T cell function. This strategy is innovative because it provides on-demand vaccine-mediated expansion in the patient. This study will provide proof-of-principle for a strategy of enhancing CAR effectiveness and augmenting T cell expansion, which could have broad application across multiple targets and disease settings.